Do any fish live in the Antarctic Ocean?

When drilling a hole almost 2,500 feet (740m) through the Antarctica’s Ross Ice Shelf – the world’s largest floating body of ice that is approximately the size of France – the last thing one might expect to find is fish swimming around. Not just any fish either, see-through fish. This was the case in January when a group of ice drillers funded by the National Science Foundation used a specially designed hot water drill to bore into an area known as the ‘grounding zone.’

The drilling site on the Whillans Ice Stream. (Photo credit: WISSARD.org)

The grounding zone is the area where glaciers and ice shelves leave the land and begin floating on the water. No one has ever drilled into the grounding zone of an ice shelf so the group of 40 explorers had no idea what to expect. There were plenty of reasons to be concerned, not the least of which being that the chosen drilling site was 621 miles (1,000km) from the closest manned base, just 391 miles (630km) from the South Pole.

A team of scientists from the University of Nebraska-Lincoln went to work drilling the hole with the same equipment used on an earlier expedition at the Whillans Ice Stream. The drill was a Kevlar hose about 4 inches in diameter and just less than a mile long that shoots a stream of hot water to melt the ice.

Breaking Through

Once the drill reached the water under the shelf a remotely-operated vehicle called Deep-SCINI (Submersible Capable of under Ice Navigation and Imaging) was dispatch down the hole. Nearly 5 feet long (1.5 m), the Deep-SCINI has imaging devices made of reinforced, pressure-resistant sapphire crystal and a streamlined body of aluminum rods and high-tech, syntactic foam comprised of millions of tiny, hollow glass beads.

The first thing observers noticed is how crystal clear the water was and the absence of any signs of life. Researchers said expected to find typical signs of life in the sea’s bottom: drag marks, meal leftovers. But the bottom of this sea was not comprised of the usual silt found in the open oceans. Instead, it is made of rock chips that are continually falling through the 33 feet of water from the bottom of the shelf, debris picked up in its journey across the land. The temperature of the water at this grounding zone is 28 degrees (minus-2 degree Celsius) adding to its inhospitable characteristics.

Six Days Later

Just after lunch on January 16, the group of researchers gathered in their small work shed as the ROV operator lowered the Deep-SCINI into the drill hole. Once the ROV righted itself and parked on the bottom it took six hours before anything happened. Then, from about 20 or 30 feet away a fish, a living fish, appeared and began slowly swimming toward the ROV.

“I have been investigating these types of environments for much of my career, and although I knew it would be difficult, I had been wanting to access this system for years because of its scientific importance,” said Ross Powell, a chief scientist with the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project and a researcher at Northern Illinois University.

The discovery of living creatures, including various types of amphipods (crustaceans) at this depth in these conditions will provide science with years of research. The absence of visible food sources and no signs of microbial or bacterial life make this an adventure in discovery for the team.

The finding of living creatures in deep water is not novel to science, but finding creatures in this type of environment was a first. Especially if you take into consideration that this grounding zone habitat is 528 miles (850km) away from any form of sunlight.

The fish are transparent. You can clearly see their insides as they swim by the camera. Scientists observed a group of about 20 or 30 of these translucent fish, noting they all have large eyes likely necessary to see in the dark waters. It is unsure if these fish will represent a new species, or classified as a notothenioid, the dominant species of fish found in the frigid coastal waters of Antarctica.

The notothenioid’s translucency is likely an evolutionary byproduct of losing hemoglobin, the protein responsible for the red color in blood. How they are able to survive in such a hostile environment is one of the many questions scientists are hoping to answer. However, there is one theory.

“Their evolutionary success is related to key adaptations, such as antifreeze glycoproteins, which prevent their body fluids from freezing at subzero temperatures,” said Reinhold Hanel, a researcher who is not affiliated with the WISSARD Project.

Due to the constant moving of the ice shelf, falling debris is never-ending. For this reason, researchers have not found, and do not anticipate ever discovering, any sedentary types of creatures.

Further Research

Researchers are hoping to find microbes in core samples drilled before sending the ROV into the abyss. Part of their research alter the global warming discussion, in particular if microbes are present and if they produce greenhouse gases such as methane and carbon dioxide. If that is the case, it could help scientists determine if these gases will be released as the ice shelf melts, a major consideration in the global warming argument.

The grounding zone environment also gives scientists a chance to learn what might be expected when exploring more far-reaching places such as Europa, Jupiter’s frozen moon which is believed to be hiding a vast ocean under its icy surface.

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